Wires wear coats

The idea

Metals are conductors of electricity, with silver, copper and gold the best electrical conductors; plastic, rubber and ceramics are electrical insulators.

A cable has two layers

Look at any electric cable. Inside is a shiny metal wire. Outside is a coloured coat of plastic or rubber.

Why do you think the outside is plastic or rubber and not metal?

• So the current cannot reach our hands
• To make the current flow faster
• Only for colour

Build a cable

Your cable has a core (the wire inside) and a cover (the outside). Change them until the cable works and is safe.

Conductor inside, insulator outside

Metals are conductors of electricity, with silver, copper and gold the best electrical conductors. Plastic, rubber and ceramics are electrical insulators.

Electrical wires, switches and the connectors of plugs and sockets are made of conductors. Insulators cover wires, plug tops and switches to protect people from electric shocks.

• Material | Conductor or insulator? | Where it is used
• Silver, copper, gold | conductors (the best ones) | the wire inside; copper is mainly used (lower cost, plentiful)
• Plastic, rubber, ceramics | insulators | covers for wires, plug tops and switches

Notes

Metals conduct (best: silver, copper, gold). Plastic, rubber, ceramics insulate and cover wires, plug tops and switches to prevent shocks.

Check yourself

Which of these are the best electrical conductors?

Why are electrical wires mainly made of copper?

Why are wires, plug tops and switches covered with rubber, plastic or ceramics?

Which part of a plug is made of a conductor?

• Silver, copper and gold — correct. Yes! These three metals conduct best.
• Plastic, rubber and ceramics. These are insulators.
• Glass, paper and wood. These are not among the best conductors.
• Copper is an insulator. Copper is a conductor.
• It conducts well, costs less than silver or gold, and there is plenty of it — correct. Yes! Lower cost and abundant supply.
• Silver and gold do not conduct. Silver and gold conduct very well. They cost much more.
• They are insulators and protect people from electric shocks — correct. Yes! The cover keeps the current from reaching us.
• They are conductors and make the current stronger. They are insulators.
• They are lighter than metal. Weight is not the reason.
• The plastic part you hold. This is an insulator that keeps us safe.
• The metal pins that fit the socket — correct. Yes! The pins carry the current.
• The rubber covering on the cord. Rubber is an insulator.